Microsoft has started shipping the first official Beta Build of its next iteration of the Office System to testers. The Redmond company is actually sending select participants, in the Office 2010 Beta testing program, the bits for the upcoming development milestone on 2GB USB devices. Michael Reza Aulia, a software Research & Development Manager in Melbourne, Australia, is one of the lucky recipients of a USB Flash drive with the official Office2010 Beta bits from Microsoft. The software giant previously informed participants of the Office 2010 Technical Preview that the Beta development milestone would be made available by the end of November.

Microsoft even revealed to the world that by the end of the month it would offer the first public Beta of Office 2010. However, Office 2010 public downloads are not live yet, with all indications pointing to the fact that the situation will change come next week, and the debut of the Professional Developer Conference 2009.

According to the screenshots posted of Office 2010 Beta, Microsoft has touched up the graphical user interface. But users should not expect a major overhaul, just a redesign as the product evolved from Technical Preview stage to Beta. Still, testers already familiar with Office 2010 will be able to notice immediately that the software giant did, in fact, revamp the icons for all the components that make up the suite. There are, of course, additional changes, but more will become visible as Office 2010 public downloads will become available next week.

Following Aulia’s report, certain websites have started reporting that Office 2010 Beta Build 14.0.4514.1009 has been leaked. And, in fact, they are perfectly right. Build 14.0.4514.1009 has been leaked since almost a month ago, in mid-November, when Wzor posted the download links to torrent trackers. Even at the time, third-party sources emphasized that Office 2010 Build 14.0.4514.1009, which was labeled Beta 2 and had made its way to BitTorrent websites, was in fact the same as the official Office 2010 Beta.

UPDATE: There are reports pointing out that Build 14.0.4514.1007 is in fact the fully-fledged Office 2010 Beta.

No official confirmation from Microsoft has been offered at this point in time of the official Build string for the Office 2010 Beta development milestone.